Particular embodiments generally relate to telecommunications and more specifically to processing a disconnect message with a progress indicator in a SIP-PSTN network.
In a SIP-PSTN network, a disconnect message with progress indicator (PI) e.g., disconnect (PI=8) may be sent by a PSTN device to a gateway. The gateway may communicate with another gateway using a different protocol, such as session initiation protocol (SIP). When the disconnect (PI=8) message is received, the gateway maps the disconnect (PI=8) to a 183 session in progress SIP message. The 183 session in progress SIP message is then sent to another gateway. That gateway maps the 183 session in progress message to a progress (PI=8) message.
The progress (PI=8) message is different from a disconnect (PI=8) message. The disconnect (PI=8) message indicates that a disconnect is desired but an in-band announcement is being provided and thus establishment of a voice path is requested. For example, this may occur when a subscriber is busy and a private branch exchange (PBX) wants to send a message indicating the subscriber is busy. When a disconnect (PI=8) message is received, a receiving PBX has the option to establish a voice path and listen to an in-band announcement or disconnect the call. In contrast, the progress (PI=8) message is just a request to establish a voice path. Because of the interworking that occurs between PSTN to SIP, the disconnect (PI=8) message is not mapped to the disconnect (PI=8) message after interworking from PSTN to SIP and back to PSTN. Accordingly, the PBX receiving the progress (PI=8) message does not know a disconnect (PI=8) message was sent. Thus, the option to disconnect is not provided to the PBX.